Vol 10 No 1-2 (2021)

Original Articles

  • XML | PDF | downloads: 139 | views: 276 | pages: 1-10
    Background:     Bacillus cereus is one of the important pathogen, which can be found in food samples like milk and principally responsible for food poisoning. Metallo-beta-lactamase (MBL) genes present in the Bacillus cereus bacterium, which provide resistance to the bacteria against the extreme condition. The objective of this study is to carry out molecular detection of blaTEM, blaCTX-M and blaSHV MBL genes in B. cereus strains, isolated from infant dry milk samples.   Methods:     Total 50 samples of infant dry milk were collected from the drug store, and 19 samples were selected for this investigation. After morphological and biochemical characterization of suspected colonies which are obtained from infant dry milk samples, these isolates were confirmed for B. cereus. Antibiotic susceptibility tests were done as per criteria of Clinical and Laboratory Standards Institute (CLSI). The phenotypic confirmatory analysis was done in Mueller Hinton agar (MHA) plates with clavulanic acid. If inhibition diameter is ≥5 mm increases in the clavulanic acid (CA) containing plate than to a plate without CA, it confirmed the presence of MBL genes. PCR used for detection of MBL genes in the isolated strains. Results:     PCR detected the blaCTX-M (100%), blaSHV (4%) and blaTEM (84.2%) gene of B. cereus in the infant dry milk. Conclusion:     The study confirms that the infant dry milk is a good source of B. cereus, if dry milk has absorbed water content from the air and hence providing a perfect condition for the growth of the bacterium, so It should be kept airtight the dry milk and stored in the cold condition.
  • XML | PDF | downloads: 134 | views: 310 | pages: 11-19
    Background:       Adding signal sequence and His- tags to the expression vectors of recombinant proteins usually increased the production yield by promoting protein secretion to the periplasmic space and by facilitating the purification processes. In this study, three different expression constructs including vectors with or without signal sequence and His-tags were designed to compare the effect of these elements on Hirudin expression and function. Hirudin is a natural anticoagulant protein produced in the salivary glands of leeches. Methods:     Hirudin variants including cytoplasmic Hirudinn without His-tag (cr-Hirudin),  cytoplasmic Hirudin with His-tag (crhis-Hirudin), and periplasmic Hirudin with His-tag (prhis-Hirudin) constructs were expressed in E.coli BL 21(DE3). Ion exchange chromatography and ion metal affinity chromatography were applied for protein purification. The prothrombin time (PT) and activated partial thromboplastin time (aPTT) assays were performed to assess the anti-thrombin bioactivity of variants. Results:     The expression rate of prhis-Hirudin was approximately 1.6 fold higher than cytoplasmic variants ( cr-Hirudin and crhis-Hirudin). The prothrombin time and activated partial thromboplastin time of crhis-Hirudin and prhis-Hirudin were similar and approximately 20 and 55 % lower than those of cr-Hirudin.Conclusion:     Applying signal peptide or His-tag increased the production yield of recombinant hirudin but had negative contributions to its activity.
  • XML | PDF | downloads: 175 | views: 365 | pages: 20-29
    Background:     The transmission of antibiotic resistance through the food chain is one of the major health challenges, worldwide. A combination of essential oils with synergistic or additive effects to enhance the antimicrobial activity, is an applied approach to improve food safety. Methods:     In this study, 93 E. coli isolated from the viscera of broilers, suspected to colibacillosis, were examined for detection of ESBL by the combined disk method according to Clinical and Laboratory Standards Institute. CTX-M was detected by PCR. Antibacterial activity of cinnamon and oregano essential oils were studied against bla CTX-M harboring isolates by broth microdilution method and fractional inhibitory concentration index. Results:     According to the results of this study, 32/93 (34.4%) of tested samples produced ESBL, and 10/32 (31.2%) harbored CTX-M. All the CTX-M producing E. coli investigated by broth microdilution assay, were sensitive to cinnamon and oregano essential oils in the range of 400 to 3200 and 800 up to 1600ppm, respectively. Fractional inhibitory concentration indices ranging from 0.5 to 1.5, suggested synergistic, and additive inhibitory effect of cinnamon and oregano essential oils. Conclusion:     The results of this study indicated that bla CTX-M might be transmitted to humans through chicken meat. The combination of cinnamon and oregano can be suggested as a safe bio-preservative which leads to growth inhibition of antibiotic resistant E. coli. However, further studies should concern the potential interaction between essential oils and food matrices.  
  • XML | PDF | downloads: 171 | views: 404 | pages: 30-47
    Background:     The exceptional properties of the silver nanoparticles play an important role in nanoscience and nanotechnology, particularly in nanomedicine and also offer several applications in the biomedicine field. The development of antibacterials which are clinically useful against bacteria and drug resistant microorganisms, it is one of the main approaches of silver nanoparticles. However, it is essential to improve environmentally friendly methods for their synthesisin this respect, the principal aim of this research is focused on to propose a simplified and efficient green synthesis of silver nanoparticles with proven antibacterial properties. Methods:     The green synthesis route is based on the use of the Ephedra sinica as reducing agent of the silver ions in aqueous solution at room temperature. Complementary, the antibacterial activity of the silver nanoparticles against E. coli, S. aureus, S. dysenteriae, B. cereus and L. monocytogenes was confirmed. Green synthesized silver nanoparticles have been characterized by UV-Vis spectroscopy, XRD, TEM and FTIR. Results:     The silver nanoparticles revealed Gaussian distributions with the average diameter of 10 nm and results showed that the lowest MIC and MBC of Ephedra sinica herb extract were 25 and 50 mg/mL, respectively and also the lowest MIC and MBC of the antibacterial activity of the silver nanoparticles produced by Ephedra sinica herb extract were 6.25 and 12.5 mg/mL, respectively. Conclusion:     The observed results suggested that using Ephedra sinica, it is possible to performed silver nanoparticles with controlled characteristics and with significant inhibitory activity against the E. coli, S. aureus, S. dysenteriae, B. cereus and L. monocytogenes.
  • XML | PDF | downloads: 124 | views: 280 | pages: 48-52
    Background:     Brucellosis is a zoonotic disease and humans get the infection mostly through consumption of raw milk. Vaccination is the best way to control brucellosis and Iran uses Rev.1 vaccine in sheep and goat flocks. It is evident that the vaccine may shed through milk so it can infect humans. The objective of the present study is to assess the shedding of the vaccine in lactating ewes and its possible immunity in their lambs through milk feeding.  Methods:     In a two-month period post-parturition, reduced dose Rev.1 vaccine was injected to 50 parturited ewes. From the first day of vaccination, mixed milk samples were collected and continued for 2 months. Then the samples were tested by PCR method and the sera from 70 lambs of the examined ewes were tested by modified Rose Bengal test while they were feeding milk. Results:     From the 6th day until the 27th day post-vaccination, PCR represented the DNA of Rev.1 in the milk samples. All the lamb’s sera were negative in the serological test.  Conclusion:     As the presence of Rev.1 in milk was confirmed in this study, it is important to consider the role of the vaccine strain as a risk of infection in humans. Moreover, as the serological response in the lambs was negative, it seems that the vaccine strain didn’t immunize the lambs through milk feeding so the vaccination of lambs is necessary in small ruminant’s flocks.
  • XML | PDF | downloads: 123 | views: 297 | pages: 53-62
    Helicobacter pylori (H. pylori) infection is one of the most common infections acquired in the community. Study after study has shown that, H. pylori plays a major role in gastritis and gastric ulcer which is result in gastric cancer. Gastrointestinal diseases are major reasons for morbidity and mortality throughout the world. Many epidemiological studies have been done up to now indicated the predominant serious prevalence of H. pylori.   The aim of this retrospective cross-sectional survey is to assess the incidence of H. pylori in Qazvin province, Iran. Methods:     A sero-epidemiological study was carried out in Qazvin, Iran. H. pylori was diagnosed using a commercially available stool antigen test (HpSA).  The H. pylori CARD Test is a rapid immune chromatography assay (ICA) test that uses a monoclonal anti-H. pylori antibody on a strip for the detection of H. pylori infections in stool specimens. Results:     In the current study the overall infection rate was calculated approximately near to 52% that is remarkable (224 out of 434 patients). Conclusion:     Accordingly, dedicating attention to further studies on the development of new strategies in order to treat and manage this bacterium through methods like Phage therapies, clustered regularly interspaced short palindromic repeats (CRISPR) and focusing on the use of microbiomes are suggested.